In many industrial processes there are produced gaseous streams which contain materials therein which must be recovered or removed. For example, in degreasing or in paint spraying operations employing a volatile solvent there is usually produced an air or gaseous stream which contains the volatilized solvent therein and usually the solvent must be removed or recovered before the air or gaseous stream is discharged into the atmosphere. The removal and/or recovery of such volatile solvents may be required by regulatory agencies to protect the environment or for economic reasons, such as the recovery of the solvent so that it can be recycled or again utilized. In many other industries, such as in the semi-conductor industry and in other processing operations, particularly in the petroleum industry, there are produced gaseous and/or liquid streams which contain materials, which must be removed or recovered.
The recovery of materials, e.g. volatile solvents or treating agents from gaseous streams, as indicated hereinabove, has been accomplished by various techniques, such as by contact with a selective solvent for the volatile component to be recovered. Another technique for the recovery of such volatile materials employs a particle form selective adsorbent, such as activated charcoal, molecular sieves, activated alumina and the like. Various techniques employed for the recovery of volatile materials from a stream containing the same are disclosed in numerous patents, U.S. Pat. Nos. 4,102,983; 4,227,891; 4,339,248; 4,265,945; 4,441,896; 4,101,297. The disclosures of the above-identified patents are herein incorporated and made part of this disclosure.
For the most part, however, the techniques and processes and equipment which have been previously employed for the recovery of volatile solvents and the like from gaseous streams containing the same have not been completely satisfactory, particularly as applied for the recovery of volatile solvents or pollutants from an air stream containing the same in a minor amount, such as an amount in the range about 5-10,000 ppm by weight or volume In connection with the recovery of valuable solvents and treating agents from such air streams or the recovery of noxious or noisome solvents and/or pollutants from such air streams, it is desirable to recover as much as possible such materials, preferably with a recovery or removal efficiency of at least about 90%, and preferably so that the resulting treated stream contains such a small amount of solvent or pollutant therein that either the economics of the process permits the discharge of the treated stream into the environment and/or the discharge thereof does not disturb the environment.
Accordingly, it is an object of this invention to provide an improved process for the recovery of materials from gaseous streams, such as air streams, containing the same.
It is another object of this invention to provide a process for the recovery of materials, such as solvents, from gaseous streams containing the same, with substantially minimum energy or heat requirements to carry out or operate the process.